Sheet detector



March 2,1937; A. WORMSJER 1 2,072,236

SHEET DETECTOR Filed Dec. 26 1935 WMMW Patented Mar. 2,1937

UNITED STATES,

PATENT OFFlCE amazes snnrzr narno'ron Arthur Wcrmser, Offenbach, near Franlx fort-onthe-Main, Germany Application December 26, 1935, Serial No. same In Germany October 7,1933 g r I provide means whereby sheets, advanced erroneously together with the sheets to be fed, will be detected.

Another object is the provision of mechanism associated; with the detecting means whereby the feeding of sheets will be interrupted in the event that more" thana predetermined sheet thickness is being fed towardssheetreglsteringmeans or the like. 1 Y

A further object oi 'theinvention isto provide simple and efl'ective apparatus adapted 101' use in 20 connection with any conventional type of sheet feeding mechanism and'whereby disturbances in the feedingof sheets will be reduced to a minimum.

Still further objects oi the invention will be apparent from the following description and appended claims.- I Q Sheet feeding apparatus, even of the most reliable type, used heretofore on printing. presses,

folding machines or the like, are subject to oc- 30 casional interruptions for reasons, such as the presenceoif more than one sheet, or of defective sheets, or sheets becoming mispositioned during their travel. Itbecomes necessary therefore to provide sheet detecting means associated with 35 suitable mechanism whereby conditions such as pointed out above will be prevented; or whereby the operation of the sheet handling machine itself will be interrupted. It is desirable to arrange sheet detecting devices at stations where it'can 40 be ascertained whether or not encess sheets are being advanced erroneously together with the, sheets to be registered. i

In sheet feeding mechanism it has been common practice heretofore to detect the position of. 45 sheets by means of mechanical or electric contact appliances. Such devices, however, are not entirely reliable and therefore they do not assure the desired results, "Some preferredarrangements for carrying my 50 invention into effectare illustrated infthe accompanying drawing,'in which:

i Figure 1. is a diagrammatic illustration of,

means specifically adapted fordetecting plural sheets whichhave'not reachedthe registering 55 guides in proper position; and r Figure'2 illustrates means similar to that shown,

in Figure 1 but applied in connection with sheet feeding mechanism whereby sheets are being ad-, .vanced to the registering guides in superimposed relation, that is to say in the form of a seriated bank of sheets.

The arrangement illustrated in Figure 1 isintended to detect whether or not more than one sheet is fed simultaneously to the registering guides 2. I have shown in addition to the top,

sheet I, an excess sheet la. which has been erroneously fed towards the registering guides and the leading edges of both sheets. are shown ad Jacent said guides. It will be seen that the beam of light and all of the parts associated with it are located preferably somewhat in advance of the front guides}. The arrangement of the cooperating parts is such that the tripping takes effect when the relay fails to-be energized and said armature moves down. Accordingly. a device must be provided which will preventthe tripping of sheet handling mechanism during the greater part of the cycle of operation of such mechanism, while-the photo-electric cell I is not energized due to the extinguishment of the electric light, the closing of the slit 6, or the covering of such slit by the shutter III. This can be accomplished-by means of cams or the like'elemerits associated with the tripping mechanism so that the latter will become effective during a predetermined period only, namely during a predetermined portion of the operating cycle of the sheet handling mechanism or machine, In Figure 1 a preferred means whereby this may be accomplished for example is shown directly associated with the armature oi the relay 9. I provide a finger I I which is intended to continually hold the armature of the relay. 9 in its upper position and said finger is lowered only during that predetermined moment duringwhich the detecting means may become eflective.

The photo-electric cell ,1 is of such character that the light rays passing through a single sheet will ,be of sufficient intensity to energize'said cell for the purpose of attracting the armature of the relay 9 and maintain it in theposition shown in Figure 1 without the aid of the finger ll.

However, when a plurality of sheets in super imposed relation are accidentally fed towards the guides 2, then the volume of light passing through such plurality of sheets will not be sumcient to energize the relay 9, and consequently the armature, as it recedes from therelay 9', will cause the tripping mechanism to operate.

My invention has proven of particular'advanassociated mechanism being shown in full lines tage when applied in connection with mechanism where superimposed sheets i. e. a seriated bankof sheets are being fed towards the registering guides. Such an arrangement is indicated in Figure 2. l

It will be seen that according to this modification, the sheets are advanced in continuous superimposed relation.

When feeding sheets in this manner, it is eviso as to act in close proximity to the front registering guides, then any misfeeding of sheets occurring intermediate said guides and the pile l2 from which they are being separated and fed, would not be detected. Therefore, any sheets that become mispositioned during their removal from the pile l2, or immediately after they have passed said pile, would continue to travel towards the front registering guides and obstruct the path of other oncoming sheets with obvious consequences.

t For this reason it is highly desirable to mount sheet detecting means in close proximity to the front edge of the pile of sheets and to trip the feeding mechanism before any misfed sheets will reach the registering guides.

I have' found that when feeding sheets in superimposed relation, it is exceedingly dimcult to provide mechanical detecting devices that can be relied upon to function satisfactorily, particularly so when arranged near the pile where the number of superimposed sheets is usually a maximum. Mechanical detecting devices which are intended to act on two or more superimposed sheets are very delicate. Such devices become more intricate as the number of superimposed sheets increase.

Because of the fact that light sensitive apparatus, such as photo-electric cells. are adapted to energize relays only above an accurately adjusted limit of light penetration, such devices are particularly well suited for use as detecting means in machines where sheets in superimposed relatio are fed.

It is evident of course that in such events the rays of light would be caused to impinge at such point or points at which normally the minimum number of sheets are superimposed. In Figure 2, I have illustrated one preferred form of such an arrangement, one of the detectordevices and and in a position intermediate the front guides 2 and the pile l2, whereas another position of such device is shown in broken'lines and located in 55 close proximity to the leading edge of said pile.

dent that if the detecting means were mounted said beam is not interrupted by a sheet. On the other hand, however, the armature of the relay 9 would move down and actuate the tripping means in'the event that the beam of light rays passing between the slit 6 and the photo-electric The arrangement of parts and operation thereof being shown preferably as identical to that de-- scribed in connection with Figure 1.

In feeding superimposed sheets it frequently 60 occurs that upon separation of the sheets from the pile, disturbances occur, because misfed or misseparated sheets may become displaced so that their lateral margins extend beyond the normal path of the sheets. By providing a source 65 of light on each side of said normal path and in close proximity to its limits, an arrangement such as is illustrated in Figure 1 could very readily be usedfor stopping the sheet handling machine or the sheet conveying apparatus in the event of 70 such displacement of sheets. In such case the cooperating parts would be so arranged that the beam of light rays passing through the shutter 5 would prevent tripping of the machine or apparatus by maintaining the relay 9 energized when- 7 ever the finger II is lowered and providing that cell 'i would become interrupted by a misfed sheet.

It will be readily understood that it would be possible to arranges. number of the disclosed detecting means and to cause the various relays to actuate a single tripping device. It is also possible to provide some detecting devices of a mechanical or electrical type and to-associate them with one or .more detecting means of a light sensitive type in such a manner that they would actuate a single tripping mechanism. Other modifications may be adopted without departing from the principle of the inventionand I therefore desire to cover any such modification that will come within the scope of the appended claims.

I claim:

1. Sheet detecting means, having in combination a source of light arranged to direct a beam I of rays through one or more sheets of material, a light sensitive element adapted to' be energized by rays of light penetrating through a predetermined plurality of sheets for the purpose of interrupting the advance of sheets in the of rays through one or more sheets of material while in motion a light sensitive element adapted to be energized by rays of light penetrating through a predetermined plurality of sheets for the purpose of interrupting the advance of sheets in the event that more than said predetermined plurality of sheets pass said beam of rays simultaneously.

3. Sheet detecting means, having in combination a source of light arranged to direct a beam of rays through one or more sheets of material, a light sensitive element adapted to be energized by rays of light penetrating through a predetermined plurality of sheets, an electric relay associated with said element for the purpose of interrupting the advance of sheets in the event that more than said predetermined plurality of sheets pass said beam of rays simultaneously.

4. Sheet detecting means, having in combination a source of light arranged to direct a beam of rays through one or more sheets of material,

for the purpose of actuating tripping means 1 whereby the operation of the sheet handling mechanism will be interrupted.

5. In a sheet-detecting means, the combination of a source of light arranged to direct a beam of light through a thickness of one ormore overlying sheets of material, and a lightsensitive element arranged to be influenced by said light-beam after it has penetrated'through said sheet thickness and, in the event more than said sheet-thickness is interposed between said source'oif light and said element, as by an additional sheet, to modify the effect of the beam on said element sufllciently' to be availed of to preclude feeding of said addcdsheet.

' aovaaae s. Sheet-detecting means, having in combination a source of light arranged to' direct a beam of rays through one or more sheets of material,

means for feeding sheets, a light-sensitive ele- .ment adapted to be energized by the rays of a 'Z. Sheet-detecting means, "having in combine tion a source of light arranged to direct a beam 1 of rays through a predetermined sheet thickness, a light-senstive element adapted to be energized by the rays of light penetrating through said sheet thickness; means for feedingand interposing sheets between said beam otrays and said element, and means for precluding the feeding of sheets, said latter means becoming eflective when more than said predetermined sheet thickness is interposed between said beam of rays and said element.

ARTHUR WORMSER. 

